Fuel pumping apparatus

Abstract

A fuel injection pumping apparatus of the rotary distributor type includes a pumping plunger (13) housed in a bore which is completely filled with fuel during the filling stroke of the apparatus. An electromagnetically operable spill valve (22) is provided to control the quantity of fuel supplied by the apparatus during the delivery stroke of the plunger. The spill valve is spring biased to the open position and is closed by an actuating member (42). If the spill valve sticks in the closed position the maximum amount of fuel will be supplied to the associated engine at each delivery stroke. A flow inhibit valve (35) is provided to control fuel flow to the bore. The flow inhibit valve is responsive to the position of the actuating member of the valve and will move to the closed position in the event that the spill valve remains in the closed position.

I claim: 
     
       1. A fuel injection pumping apparatus for supplying fuel to a compression ignition engine comprising a bore (12), a pumping plunger (13) reciprocable within the bore, the bore and plunger defining a pumping chamber, an outlet passage (15) communicating with the pumping chamber and through which during inward movement of the pumping plunger, fuel can be displaced to an associated engine, passage means (19) through which fuel can flow from a source (20) of fuel under pressure to the pumping chamber to completely fill the pumping chamber during outward movement of the pumping plunger, an electromagnetically operable spill valve (22) including an actuating member (42), for spilling fuel from the pumping chamber during the inward movement of the plunger (13) thereby to control the quantity of fuel supplied to the associated engine, characterised by a flow inhibit valve (30) incorporated into said passage means (19), said flow inhibit valve including a valve member (36, 45) movable to a closed position to prevent flow of fuel through said passage means, and means (38) movable by said actuating member (42) for controlling the setting of said valve member whereby when the spill valve is in the closed position the valve member (36, 45) will move to the closed position. 
     
     
       2. An apparatus according to claim 1, characterised in that the valve member (36, 45) is biased by a spring (37) to the closed position and is movable to allow fuel flow along said passage means by the pressure of fuel from said source (20), said means (38) acting when the spill valve is closed, to balance the fuel pressure acting on the valve member to allow the valve member to move to the closed position under the action of said spring. 
     
     
       3. An apparatus according to claim 1, characterised in that the flow inhibit valve (30) comprises a cylinder (32, 46), a valve member (36, 45) slidable in the cylinder, a first port (33, 50) at one end of the cylinder and a second port (34) in the wall of the cylinder, said first port communicating with said source (20) and the ports and cylinder forming part of said passage means, a spring (37) biasing the valve member towards said one end of the cylinder, said valve member when in engagement with said one end of the cylinder preventing flow of fuel through said first port, a restricted passage (43) connecting the other end of the cylinder with said source (20) and said means (38) defining a control valve which is open to vent the other end of the cylinder when said spill valve is open. 
     
     
       4. An apparatus according to claim 3, characterised in that said control valve includes a control element (38) movable by said actuating member (42) to uncover an opening in the other end of the cylinder when said spill valve is open. 
     
     
       5. An apparatus according to claim 4, characterised in that said spring (37) is interposed between said control element and said valve member.